The contractor will perform transverse axial tomography upon patients with stroke and compare these tomographic images with localization by clinical neurological examinations and scintillation scans in all patients with special contrast studies when clinically indicated and with autopsy findings in fatal cases. The purpose of the study is to determine the localizing capability of TAT techniques in stroke, minimal time after onset of stroke required to alter the radioabsorbency of ischemic areas to a degree permitting detection, and the limits of special resolution of the instrument in detection of minor focal vascular lesions.